The fourth season of “Mad Men” opened with a question, and a hint: “Who is Don Draper?” The primary arc of the show has been to answer that question, and the first three seasons trotted along, slowly revealing the details of Don’s shadowy past. The story behind his real name, how he met and married Betty, and his previous “marriage” all occupied the lion’s share of narrative space while the rest of SterlingCooperDraperPryce stood by and watched. But season four takes aim at a dimension of Don previously left unexplored: his psyche. And for all the time spent unpacking what Don does, little explanation has been given for what Don thinks.

Which is why the journal narrative that opens “The Summer Man,” the season’s eighth installment, is proof that the Emmy-dominating series is entering its prime. The deconstruction of a protagonist who was previously steeped in enigma and fa?ade is reaching new levels, just as the the ’60s are getting up to a gallop. “The Summer Man,” which features the Rolling Stones’ “(I Can’t Get No) Satisfaction” in its opening sequence, follows Don’s last stages of recovery with the Betty break-up. Simultaneously, Peggy and Joan wrangle with Joey’s base potty humor and their status as women playing a man’s game.

When Betty and Henry encounter Don and Bethany at the same restaurant, Betty’s immediate and alcohol-fueled breakdown signal quite clearly who’s taking things better. Betty gets driven home by an angered Henry (“Shut up Betty, you’re drunk!”) while Don gets a little more than a goodnight kiss from the previously anxious Bethany; it’s as if the mere presence of Betty was just what Don needed to get Bethany to ease up. He even snags a date with Dr. Miller, meaning he’s simultaneously dating two prior dead-ends. The old Don is back, sort of. He opts for a coffee after a brief stare-down with a bottle of Canadian Club. He’s getting the women he wants, but now with a greater pensiveness. “We’re flawed,” Don writes later, “because we want so much more.” It’s likely that Don’s journal entries will become a more regular part of the framing of the show, especially with the season gearing up for a finale in a few weeks’ time.

Meanwhile, back at the office, Joey pushes the envelope with Joan, pulling no punches with sexualized comments and insults to the point of drawing a sketch of what he believes to go on in Lane’s office when he and Joan meet. Peggy, in a typical stroke of equality-seeking, intervenes. But by solving one problem she creates another; instead of a pushover she’s now seen as uptight. Joan congratulates her for earning “humorless bitch” status, the whole episode demonstrating that the rules of engagement for office warfare are different for women. For Peggy and Joan, contempt, not respect, is often the reward for the aggressive behavior that earned Roger and Don their partnerships.